Preparation of silver coated nickel particles by thermal plasma with pre-treatment using ball milling

초록

Recently, reducing noble metals in electric devices has been identified as a key factor to lower product cost. Among these, noble metal coated particles are considered an alternative with the potential to dramatically reduce the usage of noble metals. A dense coating of noble metals over all surfaces is desirable for maintaining the properties of noble metal. However, our previous research showed that coated surfaces onto which the nanoparticles were attached were non-uniform because of evaporation of the raw materials. Therefore, in this study, we improved the coverage ratio of silver coated nickel particles using thermal plasma processing followed by ball mill pre-treatment. Silver and nickel particles were mixed using a ball mill, then injected into the thermal plasma jet. The silver particles were subsequently attached onto the surface of the nickel particles through ball mill processing, after which the silver attached nickel particles were melted through thermal plasma processing to produce silver coated nickel spherical particles. The cross section of the as-prepared particles showed a dense silver shell and nickel core, while the sintered body of the as-prepared particles showed the net-like silver covering over the nickel cores. These findings suggest that attachment of silver on nickel could lead to complete silver coatings by limiting the formation of nanoparticles. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

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